A conventional scroll-type compressor having a lower portion forming a compression mechanism and an upper portion forming a motor portion has a construction as shown in Japanese Patent Laid-Open No. 1-177452. FIG. 1 shows such a compressor in vertical section. Referring to this Figure, numeral 50 denotes a stationary scrollmember having a stationary scroll end plate 51 and a stationary scroll wrap 52. An orbiting scroll member 53 has an orbiting scroll end plate 54 and an orbiting scroll wrap 55. The stationary and orbiting scroll members mesh with each other so as to form a compression space 56. Numerals 57 and 58 denote a discharge port and a discharge communication pipe. The discharge communication pipe 58 is led out of a hermetic container 59 and is again led into the hermetic container 59. Numeral 60 denotes a mechanism for preventing the orbiting scroll member 53 from rotating about its own axis. A drive shaft 64 is borne by a bearing 61 which includes both the main bearing 62 and a sub-bearing 63. Numerals 65, 66 denote a stator and a rotor of an electric motor 67, respectively. The rotor 66 fits on the drive shaft 64 so as to transmit torque to the orbiting scroll member 53. Lubricating oil is supplied to sliding parts in the bearing from a lubricant reservoir 68 which is defined between the bearing 61 and the electric motor 67. A balance weight 69 attached to the rotor 66 of the electric motor 67 i exposed to the lubricant reservoir 68. In operation, a compressed gas discharged from the stationary scroll end plate 51 is introduced into a lower space in the hermetic container 59 and is then returned into the hermetic container 59 through the pipe 58 so as to cool the electric motor 67. Oil suspended by the discharge gas after cooling is then separated from the gas within the hermetic container 59. The gas free of oil is then delivered to the exterior of the compressor through the discharge pipe 70. Meanwhile, oil separated from the gas is collected in a lubricant reservoir 68.
This known apparatus has suffered from problems such as increase in the noise and vibration of the whole system as the pulsation by the discharged gas is directly transmitted to the exterior of the compressor. Furthermore, an additional communication pipe has to be provided for the purpose of introducing the discharged gas into the hermetic container.
Furthermore, there is a risk that, when the position where the discharged gas is returned into the hermetic container has not been adequately determined, the lubricating oil in the lubricant reservoir is blown by the returned gas so as to cause a shortage of the lubricant oil. When the gas discharge passage is formed by, for example, a pipe, the resonance vibration of the pipe is directly transmitted to the hermetic container to excite or amplify the pulsation of the pressure inside the hermetic container, with the result that the noise from the compressor is undesirably increased.
It is also to be pointed out that the balance weight exposed to the lubricant reservoir agitates the lubricating oil in the reservoir so as to incur a wasteful power loss.
Furthermore, presence of a space of a comparatively large volume under the compressor, forming a part of the discharge passage, undesirably allows stagnation of the lubricating oil contained in the discharged gas, resulting in a lowering of the level in the lubricating oil reservoir and, hence, in a shortage of the lubricating oil to be supplied to various sliding portions in the compressor.